Process of refining glyceride oils



Feb. 13, i940. B CLAYTON 2,190,590

PROCESS OF' REFINING GLYCERIDE OILS Filed April 5, 1937 0.4 Haris /ya my lso-Pfam. iff/yz 2 .3 4 fura/m 5mm 2 Alto/m Patented Feb. 13, 1940 l UNITED STATES raocEss oFnEFrNING GLYcEBmE oms Benjamin Clayton, Houston, Tex., assignor to Benning, Inc., Bono, Nev., a corporation of Nevada application Apro s, 1931, serial No. 135,143 15 claims. (ci. aso-42s) This invention relates to a process of rening glyceride oils and more particularly to a renning process employing an agent for reducing the -saponiiication of neutral oil during the neutrali- 45 zation of the free fatty acids of the unrened oil and for reducing the entrainment of free oil in resultant soap stock.

Glyceride oils in their crude or raw conditio contain varying quantities of impurities which must be removed in order to produce a commercially refined oil. Such impurities may be classified generally as (1) free fatty acids, (2) colored impurities, and (3) proteinaceous substance commonly termed gums, Inmodern refinery practice most of these impurities are usually removed by a single treatment of the oil with a refining agent, which is ordinarily an aqueous alkaline solution, such as a solution of caustic soda, followed by a separation step. In some cases the gums are precipitated by adding water or a dilute electrolyte and removed prior to the treatment with caustic soda in a "degumming process or are precipitated but left in suspension in the oil. In any case, the caustic soda of the refining solution reacts with the free fatty acid of the oil to form soap. An excess of caustic soda over that theoretically required to neutralize the free fatty acid is employed to act upon the colored impurities. Also, the gums are precipitated by the refining solution if they have not already been precipitated or removed. The soap, along with the colored impurities and gums, if present, form the soap stock which is of greater specific gravity than the rened oil and the soap stock is separated from the oil either by gravity separation or centrifugal separation. The resultant neutral oil may be subjected to subsequent operations to further bleach the same and remove small quantities of soap stock suspended in the oil. Such refining process may be either continuous or batch, or a combination of the two.

In either type of process, a substantial relining loss always occurs. Part of this loss is unavoidable and is due to the saponiiication of free fatty acids and the precipitation of gums or other impurities in the oil. However, a sub'- stantial portion of the total refining loss is due` I have found that there are certain agents which may be employed during the neutralization step to inhibit the saponication of neutral oil by the caustic soda and which assist in separating refined oil from the stop stock during the separation step. By'adding such an agent to the materials employed in the refining process so that it is present during the neutralization step both of these results can be accomplished. The agents contemplated by the present invention may be employed in either the batch or in the continuous process, or combinations of the two.

It is, therefore, another object of the present invention to provide a process for refining glyceride oils in which an agent is employed to inhibit saponification of neutral oil.

A further object of the invention is to provide a process in which an agent is employed to inhibit the entrainment of neutral oil in the soap stock.

A still further object of the invention is to provide a process in which an agent is employed for inhibiting both the saponiiication of neutral oil and the entrainment thereof in the soap stock.

Such agents may, therefore, be termed saponifloat-lon and entrainment inhibitors. The essential characteristics of such agents appear to be that they should be miscible with the alkaline solution and at least to some extent miscible with the soap stock formed during neutralization. They should have no deleterious reaction with the neutral oil and should be more volatile than the oil and soap stock so that they can be recovered by vaporization from the products resulting from the refining operation for re-use. Also the inhibiting agent employed should not interfere substantially with color removal. More importantly, 'it is believed that the saponification and entrainment inhibiting agents contemplated by this invention act to reduce the surface tensions of the materials in admixture during the process and particularly during the neutralizing step so that the contact between the caustic solution and oil can be quickly accomplished and also that they reduce the viscosity of the soap stock so Vthat it separates more easily from the neutral oil.

y I have found that alcohols which are sumciently volatile and miscible with water are` suitable. Thus monohydric alcohols, such as ethyl, butyl, isopropyl, propyl and amyl, fall within the contemplation of the present invention. The esters of these alcohols, for example, the acetic esters, may also be employed as well as poly-hydric alcohols and their esters having the requisite volatility and miscibility with water. Alcoholates such as sodium alcoholate may be substituted wholly or partly for the usual alkali reiining agents to provide the inhibiting agent since they liberate caustic alkali and alcohol upon contact with water. Mixtures of the various agents mentioned may also be employed.

Ethyl and isopropyl alcohol have been found to be the most desirable and, of these two, isopropyl alcohol has many commercial advantages because it is relatively inexpensive and easy to obtain. The invention has therefore been illustrated with reference to isopropyl and ethyl alcohol in the attached drawing, oi' which Figure 1 shows a series of curves illustrating the employment of isopropyl alcohol as an inhibiting agent with a low fatty acid oil;

Figure 2 is a similar drawing illustrating the employment of ethyl alcohol with a lo`w fattyacid oil' Figure 3 illustrates the employment of isopropyl alcohol with a high fatty acid oil; and

Figure 4 illustrates the employment 'of ethyl alcohol with a high free fatty acid oil.

In the drawing, the ordinates in all figures represent reiining'losses inv percentages by weight of the dry reiined oil. 'I'he abscissas represent the amount ofinhibiting agent employed in percentages by weight'of the crude oil. In making the determinations from which the various curves were prepared, a cottonseed oil was selected as exemplatory and caustic soda solution was employed in amount and strength required by the oiiicial reiining tables for cottonseed oil which, with the 0.9 FFA oil of Figs. 1 and 2 was 6.0% of 14 B. lye giving an excess of 0.44 caustic soda and which, with the 3.2% FFA oil of Figs. 3 and 4, was 9.2% of 18 B. lye giving an excess voz! 0.70% caustic soda. 'Ihe inhibiting agent was mixed with the caustic soda solution and this mixture poured into the crude oil. The resultant mixture was stirred for 15 minutes at 20 to 25 C. and then for 12 minutes at 64 to 65 C. The mixture of soap stock and oil was then allowed to settle and the refined oil carefully drained therefrom.

In all of the figures, the dotted lines connect the actual points determined by the analysis of the products resulting from the various refining operations. Although an attempt was made to maintain all of the other factors involved in reiining, such as temperatures, etc., constant and to make all analysis in exactly the same manner, absolute constancy of procedure was not secured. The points, therefore, do not fall exactly on a smooth curve but the solid lines have been drawn as smooth curves showing approximately the average results that may be expected.

Referring to Figure 1, curve I0 represents the total refining losses where varying proportions of isopropyl alcohol were employed in refining a low fatty acid oil. The curve Il represents the losses due to saponiiication of neutral oil while the curve I2 represents the losses due to entrainment of free oil in the soap stock. The unavoidable losses such as those due to the neutralization of free fatty acid and the precipitation of gums remain substantially constant irrespective of the proportion of alcohol employed and are not shown in the figures.

Curve I0 shows that the total loss when no alcohol was employed was approximately '7% and that the losses reached n. minimum of approximately 4% in the neighborhood of 1% isopropyl alcohol. Thus with a crude oil containing 0.9% free fatty acids and the usual amount of gums and colored impurities, the refining losa was reduced from 7% to 4%, or a total saving of 3% oi' the oil being refined. As shown by the curve Il, the -amount of saponied oil was reduced from approximately 3% to approximately 2% or a saving of approximately 1% of the oil being refined while the free oil entrained in the soap stock was reduced from approximately 2.5% to approximately 0.5%, or a saving of approximately 2% of the oil being refined. If these percentages are calculated on the basis of the total refining loss, it will be seen that the total refining loss was reduced by approximately 43%.

About the same saving was made when ethyl alcohol was employed as shown by Figure 2 in which the curve I4 represents the total refining loss with varying percentages of ethyl alcohol. the curve l5 represents the loss due to saponiiied neutral oil, and the curve I6 represents the. loss of entrainment of free neutral oil in the soap stock. It will therefore be seen that the process using ethyl alcohol with a low free fatty acid oil also enabled the refining loss to be reduced by approximately 43% of the refining loss when no inhibiting agent was employed.

The curve I1 of Figure 3 represents the total refining loss when varying quantities of isopropyl alcohol was used as the inhibiting agent with a high free fatty acid oil containing 3.2% free fatty acids. In this instance the total refining loss dropped from approximately 14% to approximately 9.5% or a saving o f approximately 4.5% of the reiined oil. 'I'his is a reduction in refining loss of approximately 33%. As shown by curves i8 and I9 of this figure, there was a saving of approximately 1.5% of the refined oil resulting from a reduction of the saponication of neutral oil, anda-saving of approximately 3% of the rening oil resulting from a reduction of the entrainment of such oil in the soap stock.

In Figure 4, curve 20 represents the total loss when ethyl alcohol was employed in varying proportions with the high free fatty acid oil, curve 2| represents the loss due to saponication of neutral oil, and curve 22 represents the loss due to entrainment of free oil in the soap stock. It will be noted that with high free fatty acid oils ethyl alcohol gave a somewhat greater saving than iso-propyl alcohol.

The following tables derived from the data of the above curves indicates the approximate savings due to the employment of the inhibitingagents described:

Refining losses- WITH 0.9 FFA on.

It will be noted, that in Figures 1 and 2 relating to an oil containing 0.9 FFA, no substantial decrease in loss was accomplished after approximately 1% of the inhibiting agent had been added, and that in Figures 3 to 4 relating to a 3.2% FFA the lowest losses were in the neighborhood of 3% of the inhibiting agent. In other words, the maximum amount of inhibiting agent which should be added is approximately equal to the amount of free fatty acids contained in the oil, and no advantage is obtained by adding more than this amount, although in many cases the addition of a somewhat greater amount does not materially affect theprocess except to render it less economical because of the cost of the greater amount of inhibiting agent and the expense of recovering the greater amount from the products of the process for re-use. It will further oe noted that the addition of even a very small amount of the inhibiting agent substantially reduces the refining losses so that in certain cases it may be desirable to add less than the preferred amount above indicated.

The above curves and table are given merely by way of example since the actual losses encountered Will depend largely upon the method of refining employed. In general, continuous processes, such as those described in my co-pending applications, Serial No. 534,533, filed May 2, 1931, and Serial No.` 685,130, filed August 14, 1933, produce lower rening losses than the conventional batch process. However, the decrease in rening loss shown by the above curves is typical -of what can be expected with any of these processes and the conventional batch process using the inhibiting agents in accordance with this invention becomes competitive with the continuous process if no inhibiting agent is employed therein. Employment of the inhibiting agent in vthe continuous process provides for still greater savings in refining losses.

As in the above examples, the inhibiting agents of the present invention may be mixed with the rening agent prior to mixing the latter with the oil to berened. For example, in conventional batch or kettle refining, the inhibiting agents of the present invention may be mixed with the usual caustic soda reiining agent prior to introducing the same into a kettle containing a large volume of oil. The conventional batch procedure may then be followed, that is, a thorough mixture may be obtained by rapid agitation at a relatively low temperature (65 to '15 F.) the mixture then being gradually heated to .115 to 135 F. under `reduced agitation. As the temperature increases, the emulsion formed by the rapid agitation begins to break. The slow agitation is continued until the particles of soap stock formed .by the "break increase in size and will settle rapidly in a sample withdrawn from the batch. The agitation and heating is then discontinued and the soap stock allowed to settle leaving the rened oil.

In such a process, the inhibiting agent enables the mixing to be effected in a shorter time and the emulsion formed by the mixing to be more easily broken. That is, in many cases the heating may be carried on for a shorter length of time and a lower :nal temperature employed. Since the greater part of the refining loss due to saponiiication of neutral oil apparently occurs during the emulsion stage and very little after a break has been effected, the employment of the inhibiting agent, by decreasing the length of time in which the mixture is in the emulsion stage, reduces the reilning loss due tosaponiflcation of the neutral oil for this reason. The inhibiting agent also appears to reduce the saponication of neutral oil merely by its presence in the mixture in some manner not entirely understood. Also, as shown by the curves, less oil is entrained in the soap stock. It is possible that the inhibiting agent prevents, to a large extent, inclusion of neutral oil within the particles of soap stock during their formation, or the prevention of entrainment may be largely due to the form of the soap stock particles or condition of the soap stock such that less neutral oil is held between the particles of soap stock. Applicant does not wish to be bound by anyv theory of operation and offers the above merely by way of possible explanation.

Alternatively, the inhibiting agent may be mixed with the neutral oil prior to the admixture of the refining reagent therewith, the necessary requirement being that the inhibiting agent be present during the neutralization step if saponiflcation of the neutral oil is to be substantially reduced. However, a reduction of the entrainment of oil in the soap stock can be secured even if an inhibiting agent is added during or after the neutralization step although difiiculty in doing this is encountered in the batch operation since rapid agitation is undesirable after the break has occurred.

In continuous operations the inhibiting agent may be mixed with a body of the neutral oil or with the refining solution prior to admixture of the oil and the refining agent. The latter is the preferred operation since the inhibiting agent is more miscible with the reiining solution than with the oil to be refined. In such continuous processes the oil and caustic solution are mixed continuously either by injecting the caustic solution into a flowing stream of the oil or by being introduced into a mechanical agitator through which the oil is being passed. Alternatively, the inhibiting agent may be introduced into a owing stream of either the oil or the caustic solution before they reach the mixing zone or it may be introduced as a separatestream into the mixing zone. Preferably the inhibiting agent is thoroughly admixed with either the oil or the rening agent before the mixing zone is reached, since this produces the greatest reduction in rening losses due to saponiflcation of neutral oil, but the introduction of the inhibiting agent at the point of mixing of continuous process the oil and caustic solution are mixed at relatively low temperatures, for example, 70 to 80 F., and then passed through a heating coil or other heating device in which the mixture is ordinarily heated to a temperature between and 160 F., or even higher, depending upon the type of oil being reilned. With certain types of oils having a low free fatty acid content and low color, for example, certain California oils, it has been found possible to satisfactorily rene the same with temperatures as low as 100 to 110 F. In processes involving a heating step after contacting the oil and refining agent, the mixture is maintained in motion during the heating step with suflicient velocity to prevent stratiiication of the soap stock and oil so that the mixture is properly conditioned for centrifugal separation. During the heating step the break occurs and the oil is delivered from the heating step to a centrifugal separator which continuously removes the soap stock from the oil.

In the latter type of continuous process, in which pre-heating is employed, at least the oil is ordinarily preheated to a temperature of to F., or even higher, depending upon the type of oil being rened although, as indicated above, lower temperatures may be employed with certain types of oil having low color and low free fatty acidcontent. Upon admixture of the pre-heated oil with the caustic solution, neutralization is extremely rapid and the break occurs almost as soon as the oil and caustic. are brought into admixture with each other. The mixture is, however, maintained in motion either in a mechanical agitator or by passing the same through a coil or other conduit With sufficient velocity to prevent stratiiication thereof so that the mixture of oil and soap stock is properly conditioned for centrifugal separation.

In these continuous processes, the presence of the inhibiting agent during the neutralization step reduces the refining loss due to saponication of neutral oil. Since the oil and caustic are pumped through the various stages of the process and are maintained under super-atmospheric pressure in a closed system, loss of the inhibiting agent due to evaporation from the process is effectively prevented. The presence of the inhibiting agent in the mixture during centrifugal separation, in some instances reduces the specific gravity of the heavier fluid in the centrifugal to such an extent that the addition of a weighting material to the mixture prior to or at the time of centrifuga-l separation is sometimes desirable, but such weighting material should not be present during the neutralization step. Such a weighting solution may be water or an aqueous solution of salts which have no deleterious reaction with the oil or soap stock. For example, salts of the alkali metals may be employed.

This difficulty can also be avoided by employing other continuous separation steps such as continuous gravity settling devices or continuous vacuum lters. Also it can be -avoided by evaporating the inhibiting agent from the mixture prior to centrifugal separation; for example, by passing the mixture through or jetting the same into a vacuum chamber under suflicient vacuum to vaporize all or a portion of the inhibiting agent. Even if the inhibiting agent is removed in whole or in part prior to centrifugal separation, a substantial decrease in the amount of neutral oil entrained in and discharged with the soap stock from the centrifugal is accomplished. That is, the presence o! the inhibiting agent during the preceding steps of the process appears to condition the soap stock for more eiective separation from the neutral oil.

If the inhibiting agent is removed by vaporization in whole or in part before separation, it may be condensed and re-used in the process. If not removed prior to separation, it is desirably removed from the products discharged from the centrifugal in order that it may be re-used in the process. Most of the inhibiting agent discharges with the soap stock and this material may be passed into or through a vacuum chamber and if necessary further heated in order to volatilize the inhibiting agent. Similarly the rened oil may be subjected to a vacuum condition and to further heating, if necessary, to volatilize the inhibiting agent contained therein. By condensing the inhibiting agent thus recovered it can be employed either in the form in which it is recovered or after purification. vIf the 'conditions of condensation are such that the inhibitving agent is diluted with water, an adjustment in the concentration of the reiining 4solution may be made to bring the mixture during the neutralization step to the proper water content for the oil being reiined.

In a similar manner, the inhibiting agent may be recovered from the products resulting from the batch process and re-used in subsequent operations. It is desirable to carry on batch rening in accordance with the present invention in a closed kettle to prevent loss of the linhibiting agent during the neutralization and heating steps. By applying a vacuum to such a kettle particularly during the settling step, a portion of the inhibiting agent may be recovered at that time although it is diicult to recover all of the inhibiting agent during the settling step because of the large volume of materials being treated and the interference with settling caused by the vaporization of the inhibiting agent.

The invention is also applicable to various cornbinations between the continuous and batch processes. For example, the oil and caustic may be 'continuously mixed at a low temperature either by injecting the caustic solution into a owing stream of the oil or by delivering streams of both materials to a mechanical agitator from which the mixture is continuously discharged into a kettle in which the heating and settling steps of the batch process are employed. Alternatively, the said mixture may be heated in a coil or other heating device such as a jacketed mechanical agitator and continuously discharged into a kettle for settling. Also, pre-heated oil may be mixed with cold or heated caustic solution in either of the ways described with respect to the continuous process and the resultant mixture continuously discharged into a kettle for the separation step. In any of these processes the inhibiting agent is desirably present during the neutralization step as above indicated and reduces the refining loss due to saponic'ationvof neutral oil as well as that due to entrainment of free oil in the soap stock.

The inhibiting agents of the present invention are applicable in the reiining of crude or degummed oils or to oils in which the gums have ben precipitated but not separated from the o This application is a continuation in part of my copending application Serial No. 119,023, filed January 4, 1937.

While I have described my invention in detail as applied to various modifications, it is understood `that my invention is not to be limited to such details but may be varied within the scope of the following claims.

I claim as my invention: l

1. In the process of refining glyceride oil containing free fatty acids which includes the steps of neutralizing said free fatty acids by mixing with said oil an excess of a refining solution of an alkali which will saponify neutral oil and thereafter separating theresultant soap stock from the neutral oil, and wherein the' oil is in a heated condition while in contact with said excess alkali, the improvement which comprises, neutralizing said acids in the presence of a small amount of a saponication inhibiting agent selected from the group consisting of the lower aliphatic alcohols and their organic esters which inhibits the saponiflcation of neutral oil by said alkali.

2. In the process of refining glyceride oil containing free fatty acids which includes the steps of neutralizing said free fatty acids by mixing with said oil an excess of a rening solution of an alkali which will saponify neutral oil and thereafter separating the resultant soap stock from the neutral oil, and wherein the oil is in a heated condition while in contact with said excess alkali, the improvement which comprises, neutralizing said free fatty acids in the presence oiV a small amount of a saponification and entrainment inhibiting agent comprising a lower aliphatic alcohol which inhibits the saponication of neutral oil by said alkali and the entrainment of free oil in the `separated soap stock.

3. In the process of rening glyceride oil containing free fatty acids which includes the steps of neutralizing said free fatty acids by mixing with said oil an excess over that required to neutralize the free fatty acids of a refining solution of an alkali which will saponify neutral oil and thereafter separating the resultant soap stock from the neutral oil, and wherein the oil is in a heated condition while in contact with said excess alkali, the improvement which comprises, neutralizing said free fatty acids in the presence of a small amount of volatile saponication inhibiting agent comprising a lower aliphatic alcohol which inhibits the saponication of neutral oil by said alkali and thereafter vaporizing said agent to separate the same from the products resulting from said neutralization.

4. In the process of refining glyceride oil containing free fatty acids which includes the steps of neutralizing said free fatty acids by mixing with said oil an excess over that required to neutralize the free fatty acids of a refining solution of an alkali which will saponify neutral oil and thereafter separating the resultant soap stock from the neutral oil, and wherein the oil is in a heated condition while in contact with said excess alkali, the improvement which comprises neutralizing said free fatty acids and separating the resultant soap stock from neutral oil in the presence of a small amount of a liquid inhibiting agent comprising a lower aliphatic alcoholl which is miscible with said refining solution and which inhibits the saponication of neutral oil and the entrainment of neutral oil in the separated soap stock.

5. In the process of refining glyceride oil containing free yfatty acids which includes the steps of neutralizing said free fatty acids by mixing with said oil an excess over that required to neutralize the free fatty acids of a refining solution of alkali which will saponify neutral oil and thereafter" separating the Vresultant soap stock from the neutral oil, and wherein the oil is in a heated condition while in contact with said excess alkali. the improvement which comprises, neutralizing said free fatty acids and separating the resultant soap stock from neutral oil in the presence o f a small amount of a lower aliphatic alcohol which inhibits the saponiiication of said neutral oil and which is miscible with said refining solution and has greater volatility than said oil .and soap stock, and evaporating said alcohol from the separated products.

6. A process of refining glyceride oil containing free fatty acids, which comprises, continuously mixing a stream of a refining solution of` an alkali which will saponify neutral oil with a stream of said oil inthe presence of a small amount of a saponication and entrainment inhibiting agent selected from the group consisting of the lower aliphatic alcohols and their esters and which is miscible with said refining solution and which is more volatile than said oil, heating said mixture and thereafter centrifugally separating the resultant soap stock from neutral oil, maintaining said mixture in motion between said mixing and said separation with suihcient velocity to prevent stratification of said oil and soap stock, evaporating at least a portion of said inhibiting agent from the materials in said process after said mixing, condensing .said inhibiting agent and returning the same to said mixing step.

7. The process of refining glyceride oils containing free fatty acids, which comprises, mixing said oil with an excess of a refining solution of an alkali which will saponify neutral oil and a small amount of a lower aliphatic alcohol which is miscible with said refining solution and more volatile than said oil and which inhibits saponication of neutral oil by said alkali so as to neutralize the free fatty acids of said oil in the presence of said alcohol, and thereafter heating said mixture and separating the resultant soap stock from neutraloil.

8. The process of refining glyceride oils containing free fatty acids, which comprises, mixing said oil with an alkali rening solution and a small amount of iso-propyl alcohol so as to neutralize the free fatty acids of said oil in the presence of said alcohol, and thereafter separating the resultant soap stock from neutral oil while the same is in a heated condition.

9. 'I'he process of refining glyceride oils containing reefatty acids, which comprises, mixing said oil with an alkali refining solution and iso-propyl alcohol so as to neutralize the free fatty acids of said oil in the presence of said alcohol, said alcohol-being present in a substantial amount up to approximately the weight of the free fatty acids contained in the oil being neutralized, and thereafter separating the resultant soap stock from neutral oil while the same is in a heated condition.

10. The process of refining glyceride oils containing free fatty acids, which comprises, mixing said oil with a rening solution of an alkali which will saponify neutral oil and ethyl alcohol so as to neutralize the free fatty acids of said oil in the presence of said alcohol, said alcohol being present in a substantial amount up to approximately the weight of the free fatty acid contained in the oil being neutralized, and thereafter separating the resultant soap stock from neutral oil while the same is in a heated condition.

11. The process of refining glyceride oils containing free fatty acids, which comprises. ccntinuously mixing a stream of a refining solution of alkali which will saponify neutral oil with a stream of said oil in the presence of a small amount of a volatile saponiflcatlon and entrainment inhibiting agent comprising a lower aliphatic alcohol so as to neutralize said free fatty acids to form soap stock without substantial saponiication of said neutral oil, continuously delivering the resulting mixture to a centrifugal separator for the continuous separation of said soap stock along with saponication and entrainment inhibiting agent and excess alkali from said neutral oil, separating said mixture at an elevated temperature and maintaining said mixture enclosed from the atmosphere during said process so as to prevent evaporation of said agent.

12. In the process of refining glyceride oil containing free fatty acids which includes the steps of neutralizing said free fatty acids by mixing with said oil an excess over that required to neutralize the free fatty acids of a refining solution of an alkali which will saponify neutral oil and thereafter separating the resultant soap stock from the neutral oil, and wherein the oil is in a heated condition while in contact with said excess alkali, the improvement which comprises, neutralizing said free fatty acids in the presence of a small amount of a lower aliphatic alcohol which inhibits the Vsaponii-lcation of said neutral oil and which is miscible with said rening solution and more volatile than said oil.

13. The process of refining glyceride oil containing free fatty acids, which comprises, mixing a lower aliphatic alcohol which is more volatile than said oil with a refining solution of an alkali which will saponify the neutral oil. thereafter mixing an excess of the resulting solution with said glyceride oil so as to neutralize the free fatty acids thereof in the presence of said alcohol, said alcohol being present in an amount substantially equal to the free fatty acids of said oil, thereafter separating the resultant soap stock from the mixture of oil and soap stock while said mixture is in a heated condition, evaporating said alcohol from the separated soap stock, condensing said alcohol and mixing the same with said rening solution.

14. 'I'he process of refining glyceride oils containing free fatty acids, which comprises, mixing said oil with an excess of a rening solution of an alkali which will saponify neutral oil and a lower aliphatic alcohol which is miscible with said refining solution and more volatile than said oil and which inhibits saponication of neutral oil by said alkali so as to neutralize the free fatty acids of said oil in the presence of said alcohol, said alcohol being present in a substantial amount up to approximately the weight of the free fatty acid contained in the oil being neutralized, and thereafter separating the resultant soap stock from neutral oil while the same is in a heated condition.

15. 'Ihe process of rening glyceride oils containing free fatty acids, which comprises, mixing said oil with an excess of a rening solution of an alkali which will'saponify neutral oil and a small amount of ethyl alcohol so as to neutralize the free fatty acids of said oil in the presence of said alcohol, and, thereafter separating the resultant soap stock from neutral oil while the same is in a heated condition.

BENJAMIN CLAYTON. 

